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21.
This paper describes the measurement of mean velocity and turbulence intensity using hot-wire anemometry inside the cylinder of a Diesel engine under motoring (non-firing) conditions. The effects of engine speed and compression ratio on mean velocity and turbulence intensity have been studied. In addition, turbulence scales have also been evaluated using auto-correlation function and power spectrum which are obtained from fluctuating velocity. The measurements were carried out at 4 different locations inside the piston cavity. Mean velocity and turbulence intensity are found to increase with speed. Increase in compression ratio has significantly increased the mean velocity at all crank angles. The main feature of this investigation is that the experiments have been conducted at higher compression ratios and a relatively high speed using a single high temperature straight wire probe.List of symbols
A
constant
-
B
constant
-
D
hot-wire diameter
-
F(f)
normalized one-dimensional energy spectral density function
-
f
frequency
-
i
current through the hot-wire
-
k
thermal conductivity of air at any temperature
-
k
0
thermal conductivity of air at reference temperature
-
L
hot-wire length
-
L
t
macro or integral time scale of turbulence
-
L
x
macro or integral length scale of turbulence
-
N
number of cycles
-
Nu
Nusselt number
-
n
constant
-
R
hot-wire resistance
-
Re
Reynolds number
-
R ()
auto-correlation coefficient
-
T
period of measurement and temperature
-
T
0
reference temperature
-
T
g
cylinder gas temperature
-
T
w
hot-wire temperature
-
U
instantaneous velocity
-
U
mean velocity
-
u
I
fluctuating velocity
-
u
turbulence intensity
-
t
absolute viscosity of air at any temperature
-
0
absolute viscosity of air at reference temperature
-
engine crank angle
-
correlation time
-
t
micro-time scale of turbulence
-
x
micro-length scale of turbulence 相似文献
22.
23.
Bijendra Kumar M. Sampath Shekhar Kumar D. Sivakumar U. Kamachi Mudali R. Natarajan 《Journal of Radioanalytical and Nuclear Chemistry》2011,289(3):861-864
Recently authors demonstrated direct dissolution of g-level PHWR UO2 fuel pellet fragments and in situ extraction by TBP-HNO3 and TiAP-HNO3 solutions at atmospheric pressures. Extending the work, similar studies were performed on intact unirradiated PHWR UO2 fuel pellets (~15 g U) with varying compositions of organic solvate of tri-n-butyl phosphate (TBP). It was observed that extent of dissolution was a strong function of organic solution composition TBP·(HNO3)
x
(H2O)
y
. Complete dissolution of intact UO2 pellet in a reasonable time was observed only in case of a particular solvate composition. 相似文献
24.
25.
A nonlinear flow of Jeffrey liquid with Cattaneo-Christov heat flux is investigated in the presence of nanoparticles. The features of thermophoretic and Brownian movement are retained. The effects of nonlinear radiation, magnetohydrodynamic (MHD), and convective conditions are accounted. The conversion of governing equations into ordinary differential equations is prepared via stretching transformations. The consequent equations are solved using the Runge-Kutta-Fehlberg (RKF) method. Impacts of physical constraints on the liquid velocity, the temperature, and the nanoparticle volume fraction are analyzed through graphical illustrations. It is established that the velocity of the liquid and its associated boundary layer width increase with the mixed convection parameter and the Deborah number. 相似文献
26.
N. Sampath S. M. Malathy Sony M. N. Ponnuswamy M. Nethaji 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(6):o346-o348
The piperidine ring in the title compound, C22H28N4S, exhibits a chair conformation. The thiosemicarbazone moiety adopts an extended conformation, and the planar phenyl rings are oriented equatorially with respect to the piperidine ring. Two intermolecular hydrogen bonds involving the S atom form molecular pairs, and the crystal structure is stabilized by weak C—H⃛π interactions in addition to van der Waals forces. 相似文献
27.
A new piperazinium 4-nitro phenolate monohydrate single crystal (PNP) was grown by employing the solution growth technique piperazine and 4-nitrophenol, were the source material used for the growth, acetonitrile is used as solvent. The grown crystal was characterized by Single X-ray analysis and it shows that piperazinium 4-nitrophenol monohydrate crystallizes in the monoclinic space group P2 1/c, with cell parameters a=10.902 5(4) Å, b=6.226 1(3) Å, c=14.031 8(5) Å, and z=4. The lattice parameters of the substances were also determined by using powder diffraction methods. The functional groups are identified by using FTIR spectral analysis. The absorbance of title compound were analyzed using UV-Vis spectra. The thermo analytical properties of the crystal were studied using TG, DTA. 相似文献
28.
Abstract
Two crystal structures of acridinediones namely, TMHAD and MPHAD were studied by X-ray crystallographic method in view of their occurrence in numerous commercial products including pharmaceuticals, fragrances and dyes. Crystal data of TMHAD are: C17H23NO2, orthorhombic, Fdd2, with cell parameters a = 40.417(6) ?, b = 5.744(1) ?, c = 12.979(2) ?, V = 3013.1(7) ?3, Z = 8, Dcal = 1.205 Mg/m3, μ = 0.078 mm−1. Crystal data of MPHAD are: C20H18NO3; monoclinic, P21/c with cell parameters a = 10.182(9) ?, b = 17.105(14) ?, c = 10.895(9) ?, β = 117.857(1)°, V = 1678(2) ?3, Z = 4, Dcal = 1.268 Mg/m3, μ = 0.085 mm−1. Both data were collected using λ (MoKα) = 0.71073 ?. The central ring in the acridinedione moieties tends to be planar while the outer two rings adopt sofa conformations. Intermolecular interactions of C–H···O type of hydrogen bond help the molecules to stabilize into the crystal packing. Interestingly, a week forces of C–H···π interactions also helps the molecules for stabilization. 相似文献29.
Surface segregation of Ge is seen in the Cu-5at%Ge alloy with an activation enthalpy equal to 17 kJ/mol. Oxidation of the alloy in the temperature range 400 to 600 K shows the formation of Cu2O and GeO which on further heating in vacuum at 650 K converts to GeO2 with the reduction of Cu2O to Cu. 相似文献
30.
Bharathi S. Sampath S. Gun J. Rabinovich L. Wu Z. Pankratov I. Lev O. 《Journal of Sol-Gel Science and Technology》1998,13(1-3):241-244
Three types of reagentless glucose biosensor based on composite graphite-ormosil materials are described: (1) a redox modified silicate-graphite electrode doped with glucose oxidase, (2) a methyl silicate-graphite material doped with redox modified glucose oxidase, and (3) a methyl silicate and redox modified graphite composite material doped with glucose oxidase. 相似文献